That's uprating to 165%, vs Merlin's 248%. It's still pretty impressive, though not taken as far.

I'm pretty sure that they put Merlin into production and use far earlier in its life-cycle than any of the old-space engines. They had something that was good enough and started using it, while the old-space engines were analyzed and engineered to a ridiculous degree before anyone even built one.

That seems like the opposite direction you'd expect things to go. As rocket engineering and modeling improve, you'd expect the first built design to be closer to the eventual limit. IOW, back in they day they had to be very conservative in their estimates and overdesign the hell out of their engines but with modern engines, they should have more confidence in their simulations and basic design.

Of course, he should be using the oh-so-common Mg unit. That's a Mega Gram, or exactly 1 metric ton. Can't use MT since the magnet-heads took that one first, even though Megatesla's don't seem to come up nearly as often as the Metric Ton (or is it Metric Tonne)?

I am sure that internally they use sensible like kN, but that really doesn't register with the common public nearly as well as Tons, which is easier to reason about (for us plebes).

My understanding was the the goofy units mostly came up in 'legacy' settings where there's a need to interface with things already built around imperial-derived units, while clean-sheet design and development prefers metric as long as one's not reliant on parts suppliers who'll stick with imperial. That would favor metric in the SpaceX engine-design case, I think, since everything going on that is new and bespoke.

My understanding was the the goofy units mostly came up in 'legacy' settings where there's a need to interface with things already built around imperial-derived units, while clean-sheet design and development prefers metric as long as one's not reliant on parts suppliers who'll stick with imperial. That would favor metric in the SpaceX engine-design case, I think, since everything going on that is new and bespoke.

They're still hiring from a US workforce and have much higher barriers compared to other industries for hiring internationally. Units die hard.

I mean shit, when I look up water stats in the US it's in acre-feet. I burst out laughing the first time I saw that. It's all just part of the fractal insanity of living here.

Mechanical engineering in the US is particularly bad. Ton as a unit of force at least has some intuitive meaning, but the first time someone used "ton" as a unit of power I had to to stop and ask them to clarify. Turns out its 3.517 kW (or 3.861 kW if its a metric ton of power).

I mean shit, when I look up water stats in the US it's in acre-feet. I burst out laughing the first time I saw that. It's all just part of the fractal insanity of living here.

Mechanical engineering in the US is particularly bad. Ton as a unit of force at least has some intuitive meaning, but the first time someone used "ton" as a unit of power I had to to stop and ask them to clarify. Turns out its 3.517 kW (or 3.861 kW if its a metric ton of power).

Acre feet are useful in agriculture and hydrology. The US is platted in feet and miles, so it's quite convenient for land use. I suspect that platting is why we didn't go metric under Nixon. I don't know how much it affected Canada.

A ton of refrigeration (TR), also called a refrigeration ton (RT), is a unit of power used in some countries (especially in North America) to describe the heat-extraction capacity of refrigeration and air conditioning equipment. It is defined as the rate of heat transfer that results in the freezing of 1 short ton (2,000 lb; 907 kg) of pure ice at 0 °C (32 °F) in 24 hours

I mean shit, when I look up water stats in the US it's in acre-feet. I burst out laughing the first time I saw that. It's all just part of the fractal insanity of living here.

Mechanical engineering in the US is particularly bad. Ton as a unit of force at least has some intuitive meaning, but the first time someone used "ton" as a unit of power I had to to stop and ask them to clarify. Turns out its 3.517 kW (or 3.861 kW if its a metric ton of power).

You're referring to tons of refrigeration. It's the power required to freeze a ton of water in a day starting at 32F or in the case of metric tons, at 0C. I think it's stated that way because it refers to output capacity of the cooler, not to the input power which varies according to the efficiency of the cooler.

Just another example of the penchant of each industry, but especially those dealing with energy and power, to invent their own units instead of using well-established ones. There was never any need to invent ergs, horsepower, tons of refrigeration, British thermal units, kilowatt-hours, tons of TNT, calories, Calories, therms, or (I shit you not) cubic mile of oil.

The measurement of an "oil barrel" originated in the early Pennsylvania oil fields. The Drake Well, the first oil well in the US, was drilled in Pennsylvania in 1859, and an oil boom followed in the 1860s. When oil production began, there was no standard container for oil, so oil and petroleum products were stored and transported in barrels of different shapes and sizes. Some of these barrels would originally have been used for other products, such as beer, fish, molasses or turpentine. Both the 42-US-gallon (159 l) barrels (based on the old English wine measure), the tierce (159 litres) and the 40-US-gallon (151.4 l) whiskey barrels were used. Also, 45-US-gallon (170 l) barrels were in common use. The 40-gallon whiskey barrel was the most common size used by early oil producers, since they were readily available at the time.

Around 1866, early oil producers in Pennsylvania came to the conclusion that shipping oil in a variety of different containers was causing buyer distrust. They decided they needed a standard unit of measure to convince buyers that they were getting a fair volume for their money, and settled on the standard wine tierce which was two gallons larger than the standard whisky barrel. The Weekly Register, an Oil City, Pennsylvania newspaper, stated on August 31, 1866 that "the oil producers have issued the following circular:"

Whereas, It is conceded by all producers of crude petroleum on Oil Creek that the present system of selling crude oil by the barrel, without regard to the size, is injurious to the oil trade, alike to the buyer and seller, as buyers, with an ordinary sized barrel cannot compete with those with large ones. We, therefore, mutually agree and bind ourselves that from this date we will sell no crude by the barrel or package, but by the gallon only. An allowance of two gallons will be made on the gauge of each and every 40 gallons in favor of the buyer.

and by that means King Richard III's English wine tierce became the American standard oil barrel.[15]

By 1872, the standard oil barrel was firmly established as 42 US gallons.[16] The 42-gallon standard oil barrel was officially adopted by the Petroleum Producers Association in 1872 and by the U.S. Geological Survey and the U.S. Bureau of Mines in 1882.[9]

I am going to be very amused if ULA starts buying Raptors for their launches.

There's a long development cycle here though. First BE-4 isn't scheduled to fly on anything before 2021. I imagine ULA needs that long to design and build their test article vehicles that will integrate the BE-4. I imagine your amusement is a thought experiment only, and not something you see happening?

I am going to be very amused if ULA starts buying Raptors for their launches.

There's a long development cycle here though. First BE-4 isn't scheduled to fly on anything before 2021. I imagine ULA needs that long to design and build their test article vehicles that will integrate the BE-4. I imagine your amusement is a thought experiment only, and not something you see happening?

That's probably one of the most impressive achievements SpaceX has ever made, but testing at a silly high pressure on a test stand is one thing. RD-180 flies like it.

Still, you'll find my admiration for Russian rocket engineers in many posts around these parts, even matching their 1970s achievements is damn good rocketry.

Musk seems to realise that he needs a proper engine if he's serious about space. Merlin was damn good for a startup, and pioneered a lot of new ways to fabricate engines, but it was still a late 1950s design, needing to build a bigger rocket to launch the same payload.... Which got SpaceX the experience in building big rockets, enabling them to skip Falcon 5.

Falcon 9 is an incredibly advanced implementation of quite crude rocketry (that same crude "just build it bigger" got man on the Moon, though!), while Raptor will power a much more modern rocket, as viewed from a pure rocketry standpoint.

With reusability being pretty routine now, the huge expense of engines like Raptor (and the somewhat similar RS-25 Hydrolox) becomes not a big deal. Raptor makes Delta-IV's cheap RS-68 look every bit the crude 1970s thing it is. With Raptor, the US has an engine which can compete against RD-180 and LE-7 (Japan's heavy lifter) on a level playing field and win.

Welcome back to cutting-edge rocketry, Americans!

(P.S. As a Brit, you will note we developed and then abandoned an independent orbital capability. This riles us up.)

When he wants more thrust, Ivan doesn’t look for a fancy propellant with a higher specific impulse. He just builds himself a bigger rocket. Maybe he’s got something there.

Apparently this isn't the case anymore.

Heh. It wasn't even necessarily up to date when the book was originally published in 1972, as the Soviets were using oxygen rich staged combustion already at that point. But, the sophistication of their staged combustion engines would remain unknown to the west until the 1990s.

When he wants more thrust, Ivan doesn’t look for a fancy propellant with a higher specific impulse. He just builds himself a bigger rocket. Maybe he’s got something there.

Apparently this isn't the case anymore.

Heh. It wasn't even necessarily up to date when the book was originally published in 1972, as the Soviets were using oxygen rich staged combustion already at that point. But, the sophistication of their staged combustion engines would remain unknown to the west until the 1990s.

Well the quote was talking about propellants. The Soviets did some pretty amazing stuff using kerolox and hydrazine pretty basic propellants. Hell it took them quite a while to even use hydrolox for upper stages and even today that isn't universal on Russian designs. The US spent quite a bit of time and research trying to come up with better propellants and that essentially was all a complete waste of time and money. Even the US infatuation for hydrolox launchers was pretty much a bust.

I am going to be very amused if ULA starts buying Raptors for their launches.

ULA has no reason to regret buying BE-4. It's a very good engine at a very good price, and by Blue Origin's own statement it's "medium-performing version of a high-performance architecture", so presumably there's the potential for upgrades in the future. Considering their only other apparent alternative was AR1 (not that it necessarily would be a bad engine, just probably more expensive and not available nearly as soon), I'd say they're damned fortunate to have BE-4.

I am going to be very amused if ULA starts buying Raptors for their launches.

ULA has no reason to regret buying BE-4. It's a very good engine at a very good price, and by Blue Origin's own statement it's "medium-performing version of a high-performance architecture", so presumably there's the potential for upgrades in the future. Considering their only other apparent alternative was AR1 (not that it necessarily would be a bad engine, just probably more expensive and not available nearly as soon), I'd say they're damned fortunate to have BE-4.

Both BE-4 and Raptor should be excellent engines.

One of those, however, you can buy. The other is from a company intending to consume its entire supply.

The memo to Wilson was signed by Michael Roark, deputy for intelligence and special program assessments. It didn’t give a reason for what prompted the evaluation. Bruce Anderson, a spokesman for the inspector general, didn’t have an immediate comment as to what led to the evaluation.

SpaceX officials declined to comment. Air Force spokesman Brigadier General Edward Thomas said the service didn’t have an immediate comment.

This looks like political kaka. If there were a specific technical concern it would be known and they would be de-certed - or whatever the term might be - already, no?

One of those, however, you can buy. The other is from a company intending to consume its entire supply.

Fair to say. Though I would imagine SpaceX might be willing to sell the engine and expand their manufacturing capacity if they had a chance to generate more revenue on a consistent basis. Who knows - they might be in that position - once they've flown it and proved its capability.